Field of the Invention
The present invention relates to a composition for a reflection film for a light emitting element, a light emitting element, and a method of producing a light emitting element. Specifically, the present invention relates to a composition for a reflection film for a light emitting element that has an electro-conductive reflection film that efficiently reflects light from a light emitting layer, the light emitting element, and a method of producing the same.
Description of Prior Art
In accordance with the recent trend of enhanced brightness, light emitting elements, specifically, LED light sources are utilized in various fields. Specifically, in accordance with development of practical white color LED light source, the LED light sources are used in applications such as lighting equipment and back lights of liquid crystal displays.
Effective utilization of emission from the LED element, a light emitting layer, is investigated in order to enhance brightness or the like of the LED light source. Patent Reference 1 discloses a LED light source that has a substrate, a LED element disposed on the support substrate, an encapsulat including a fluorescent agent, an Ag plate electrode film that is disposed between the substrate and the LED element and reflects the light emission of the LED element, and a titanium thin film disposed on the Ag plate electrode film.
In this LED light source, a layer of electro-conductive reflection film is disposed between the substrate and the LED element. By this constitution, the emission intensity is enhanced by effective reflection of light from the light emitting material (luminous material). Here, the Ag thin film and the titanium thin film are formed by a plating method or a vacuum deposition method.
In general, complicated process and generation of liquid waste are anticipated in the plating process. Large cost is required for the vacuum deposition process so as to maintain and operate a large sized vacuum deposition apparatus. The above-described LED light source requires the titanium thin film since the Ag plate electrode film alone cannot escape occurrence of thermal deterioration and/or photo deterioration. Therefore, a plating process is required together with the vacuum deposition process.
The Patent Reference 2 discloses a method of producing a LED device including disposing a LED element on a substrate, forming a wire bonding, and forming a SiO2 coating.
This method of producing a LED device also uses a silver plate film. In addition, since the SiO2 coating is formed after the disposition of the LED element, there is a possibility of contamination of the LED element during applying the SiO2 coating solution, resulting in deterioration of the yield rate.